u can tape over the heat tape and black and copper. it's the exposed area that u cannot have metal-on-metal contact like where the copper is cut at the corners. that should be covered w/ insulation like electrical tape. the black heating element and copper are all sealed except where it is cut to size or pierced or hole punched. i prefer to place the thermostat probe in the center of all heat tape or heat mats.
Edit: did the THG come pre-wired or do u know how to wire it? b/c i imagine if it came pre-wired, the vendor/seller would of taped/insulated the corners for u already.